[PATCH v5 10/13] samples: ftrace: Make the direct-call trampolines Tasks Trace readers

[bot+bpf-ci at kernel.org]

> commit 1deb3b548a13555ffd63d9373f054d6da02ad75e
> Author: Josef Bacik <josef at toxicpanda.com>
> Date:   Tue Sep 22 02:23:29 2026 +0000
>
>     samples: ftrace: Make the direct-call trampolines Tasks Trace readers
>
>     The sample direct trampolines are exactly the kind of out-of-line
>     register_ftrace_direct() user whose lifetime depends on Tasks RCU
>     waiting for a task inside them: nothing else stops rmmod while a task is
>     preempted in my_direct_func().  On HAVE_RCU_TRAMPOLINE_READERS
>     architectures that wait only covers Tasks Trace RCU readers, so give the
>     samples a small shared header with rcu_read_lock_trace() and
>     rcu_read_unlock_trace() open-coded as instruction strings for x86-64 and
>     arm64 -- the same sequences as ftrace_64.S and entry-ftrace.S, using
>     caller-saved non-argument scratch registers -- and bracket every
>     call-out with them.  The instructions outside the bracket are module
>     text, covered by ftrace_direct_mark_module().  Other architectures get
>     empty definitions.
>
>     Assisted-by: LLM
>     Signed-off-by: Josef Bacik <josef at toxicpanda.com>

This looks like a bug fix for the direct trampoline lifetime issue.
Should this include:

  Fixes: 32999f49426a ("rcu-tasks: Add a Tasks RCU implementation for reader-marked trampolines")


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